2 FreeRTOS V7.4.2 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not it can be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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76 * High frequency timer test as described in main.c.
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79 /* Scheduler includes. */
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80 #include "FreeRTOS.h"
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82 /* The set frequency of the interrupt. Deviations from this are measured as
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84 #define timerINTERRUPT_FREQUENCY ( 20000UL )
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86 /* The expected time between each of the timer interrupts - if the jitter was
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88 #define timerEXPECTED_DIFFERENCE_VALUE ( ( unsigned short ) ( ( configPERIPHERAL_CLOCK_HZ / 8UL ) / timerINTERRUPT_FREQUENCY ) )
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90 /* The highest available interrupt priority. */
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91 #define timerHIGHEST_PRIORITY ( 15 )
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94 #define timerTIMER_3_COUNT_VALUE ( *( ( unsigned short * ) 0x8801a ) ) /*( CMT3.CMCNT )*/
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96 /*-----------------------------------------------------------*/
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98 /* Interrupt handler in which the jitter is measured. */
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99 static void prvTimer2IntHandler( void );
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101 /* Stores the value of the maximum recorded jitter between interrupts. This is
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102 displayed on one of the served web pages. */
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103 volatile unsigned short usMaxJitter = 0;
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105 /* Counts the number of high frequency interrupts - used to generate the run
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107 volatile unsigned long ulHighFrequencyTickCount = 0UL;
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109 /*-----------------------------------------------------------*/
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111 void vSetupHighFrequencyTimer( void )
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113 /* Timer CMT2 is used to generate the interrupts, and CMT3 is used
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114 to measure the jitter. */
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116 /* Enable compare match timer 2 and 3. */
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120 /* Interrupt on compare match. */
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121 CMT2.CMCR.BIT.CMIE = 1;
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123 /* Set the compare match value. */
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124 CMT2.CMCOR = ( unsigned short ) ( ( ( configPERIPHERAL_CLOCK_HZ / timerINTERRUPT_FREQUENCY ) -1 ) / 8 );
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126 /* Divide the PCLK by 8. */
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127 CMT2.CMCR.BIT.CKS = 0;
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128 CMT3.CMCR.BIT.CKS = 0;
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130 /* Enable the interrupt... */
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131 _IEN( _CMT2_CMI2 ) = 1;
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133 /* ...and set its priority to the maximum possible, this is above the priority
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134 set by configMAX_SYSCALL_INTERRUPT_PRIORITY so will nest. */
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135 _IPR( _CMT2_CMI2 ) = timerHIGHEST_PRIORITY;
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137 /* Start the timers. */
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138 CMT.CMSTR1.BIT.STR2 = 1;
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139 CMT.CMSTR1.BIT.STR3 = 1;
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141 /*-----------------------------------------------------------*/
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143 #pragma interrupt ( prvTimer2IntHandler( vect = _VECT( _CMT2_CMI2 ), enable ) )
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144 static void prvTimer2IntHandler( void )
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146 volatile unsigned short usCurrentCount;
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147 static unsigned short usMaxCount = 0;
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148 static unsigned long ulErrorCount = 0UL;
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150 /* We use the timer 1 counter value to measure the clock cycles between
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151 the timer 0 interrupts. First stop the clock. */
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152 CMT.CMSTR1.BIT.STR3 = 0;
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155 usCurrentCount = timerTIMER_3_COUNT_VALUE;
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157 /* Is this the largest count we have measured yet? */
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158 if( usCurrentCount > usMaxCount )
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160 if( usCurrentCount > timerEXPECTED_DIFFERENCE_VALUE )
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162 usMaxJitter = usCurrentCount - timerEXPECTED_DIFFERENCE_VALUE;
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166 /* This should not happen! */
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170 usMaxCount = usCurrentCount;
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173 /* Used to generate the run time stats. */
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174 ulHighFrequencyTickCount++;
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176 /* Clear the timer. */
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177 timerTIMER_3_COUNT_VALUE = 0;
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179 /* Then start the clock again. */
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180 CMT.CMSTR1.BIT.STR3 = 1;
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